2015 Ford F-150 — Spark Plug Type & Gap Specs

As an ASE-certified master technician, I've seen my fair share of misfires, sluggish acceleration, and check engine lights traced back to neglected spark plugs. When it comes to the 2015 Ford F-150, keeping your ignition system in top shape is critical to maintaining the towing power, fuel economy, and reliability you expect from your truck.

Whether you're running the workhorse naturally aspirated V6, the legendary 5.0L Coyote V8, or one of the twin-turbo EcoBoost powerplants, knowing the correct spark plug specifications is your first step to a successful tune-up.

Quick reference

Below is the definitive spark plug specification chart for all 2015 Ford F-150 engine options.

Note: EcoBoost engines technically have a 100,000-mile factory interval, but due to turbocharging pressures, replacement at 60,000 miles is highly recommended by technicians to prevent misfires.

Why the right plug matters

Modern engines are incredibly sensitive to ignition components. Using the correct heat range ensures the plug runs hot enough to burn off carbon deposits but cool enough to prevent pre-ignition (engine knock).

The 2015 F-150 requires iridium spark plugs from the factory. Unlike older copper plugs (which wear out in 30,000 miles) or platinum plugs, iridium is exceptionally dense and resistant to spark erosion. This is especially vital for the EcoBoost engines, where high cylinder pressures demand a strong, consistent spark. Downgrading to copper or platinum will result in rapid gap erosion and inevitable misfires under heavy load.

How to gap a spark plug

Even if your new Motorcraft or NGK plugs say "pre-gapped" on the box, they can be bumped and knocked out of spec during shipping. Always verify the gap before installation.

1. Use the right tool: For fine-wire iridium plugs, avoid the cheap coin-style gappers, as they can snap the fragile iridium center electrode. Use a wire-type feeler gauge.
2. Check the gap: Slide the appropriate wire between the center electrode and the ground strap. It should drag slightly.
3. Adjusting the gap: If the gap is too tight, use the bending tool on your gapper to gently pull the ground strap back. If it's too loose, lightly tap the ground strap on a soft wooden workbench. Never press directly on the center electrode.

Replacement procedure tips

The 2015 F-150 utilizes a Coil-On-Plug (COP) ignition system, meaning there is no distributor or high-tension spark plug wires. Each cylinder has its own ignition coil sitting directly on top of the plug.

• Removal: Always blow out the spark plug wells with compressed air before loosening the plugs to prevent dirt from falling into the cylinders. Use a 5/8-inch magnetic spark plug socket.
• The Anti-Seize Debate: Ford factory service manuals advise against using anti-seize on the spark plug threads. The OEM plugs feature a nickel-plated coating that prevents seizing. Adding anti-seize acts as a lubricant, which can easily cause you to over-torque the plug and strip the aluminum cylinder head threads. Install them dry.
• Dielectric Grease: Apply a small pea-sized amount of dielectric grease inside the tip of the rubber coil boot. This prevents moisture intrusion, stops carbon tracking, and prevents the boot from welding itself to the porcelain over the next 100,000 miles.

Known issues

Many Ford truck owners are haunted by the infamous 2004–2008 3-valve 5.4L engines, known for 2-piece spark plugs with shells that would break off inside the cylinder head, requiring special extraction tools. Fortunately, the 2015 F-150 engines do not suffer from this broken plug shell issue. They use a standard 1-piece plug design.

However, the EcoBoost V6 engines have their own quirks. The high boost pressures are notorious for "blowing out" the spark if the gap gets even slightly too wide. If you experience a shudder or misfire during heavy acceleration (like merging on a highway or towing), your EcoBoost plugs likely have worn gaps or carbon tracking down the porcelain insulator. Tightening the gap to the lower end of the spec (0.028 in) and replacing the coil boots usually resolves this.

Need plugs replaced? Find a shop on Repairius.